SWG, Too High or Off

[ibseanb]

Hey all. Last year I was fighting algae all summer. I bought the house a year before and didn't know anything about it, everything worked fine the year before.

It turns out that suddenly my SWG would only produce for a few hours, then when switching polarity, it would go into "service mode". No chlorine = bad time.

Long story short, I purchased the same 760 model from CMP. Instantly I was back in business. Well, it turns out, I did have a 760 unit, but only a 5 plate cell (not the 7 plates that come with a new 760). It was generating so much chlorine that I could barely keep it on without having a dangerous amount of chlorine in the pool. I decided to cut 2 of the plates (the outermost plate on each side) off to make it a 5 plate cell on a recommendation of my local pool installer.

They said they install a 5 plate cell for my size of pool (16k gallons), and that a 3 plate cell (what CMP recommends for my size pool), may not keep up if there was high demand after a pool party or whatever.

5 plates works but it still produces too much chlorine. With the automatic cover closed, the SWG will create enough that its over 10ppm overnight. I open the pool and turn it off, and in a few hours it's back to acceptable levels.

A few questions.

1) If I cut off another plate to make 4, will that work, or does it need to be an odd number?
2) Would I be better off just doing 3 plates and substituting liquid shock when needed?
3) Currently the SWG builds up a ton of calcium and spits it all over the steps and floor of the pool. I'm assuming that it's because of the high output, but is there something off with the water that would make it build up so quickly?

Thanks in advance,

Sean

 

[markayash]

Do you have a timer on your SWG? Can't you just set it to run less per day?

 

[reggiehammond]

FC at 10ppm? Who cares - depending on CYA levels that may not even be enough.

Sounds like your pool chemistry is out of whack if you have scaling and you’re focusing on the wrong thing. FC is your friend - there’s many ways to tune to the right level.

By cutting off plates, you’re just throwing away money.

 

[ibseanb]

My SWG is hard wired to the same 220 as my pump, which runs continuously. I purchased a 120/220 timer last year that I didn't hook up yet because I figured plate reduction is easier.
My CYA is a bit low, but since I don't have a problem keeping chlorine... I've not worried about it.
What pool chemistry in particular would cause such calcium buildup? My water supply has high alkalinity, so it's always a bit high. Water is crystal clear.

 

[Mdragger88]

do u have any current test results?
Cya
Fc
Ch
Ph
Ta
Fc being “dangerously high” may or may not be true based upon your cya level FC/CYA Levels
It is safe to swim w/ fc anywhere between minimum & slam level for your cya.
The calcium flakes are likely another balance issue all together .

 

[Mdragger88]

What pool chemistry in particular would cause such calcium buildup?

Calcium Saturation Index (CSI)

How is CSI calculated? Very simple – by using the PoolMath tool. To ensure long plaster life and save money, click here to learn more

www.google.com

 

[reggiehammond]

My SWG is hard wired to the same 220 as my pump, which runs continuously. I purchased a 120/220 timer last year that I didn't hook up yet because I figured plate reduction is easier.
My CYA is a bit low, but since I don't have a problem keeping chlorine... I've not worried about it.
What pool chemistry in particular would cause such calcium buildup? My water supply has high alkalinity, so it's always a bit high. Water is crystal clear.

CSI - can be tracked in pool math. Want to stay 0 to -0.3 to avoid swcg scaling.

What test kit do you use?

 

[Mdragger88]

FC at 10ppm? Who cares - depending on CYA levels that may not even be enough.

Sounds like your pool chemistry is out of whack if you have scaling and you’re focusing on the wrong thing. FC is your friend - there’s many ways to tune to the right level.

By cutting off plates, you’re just throwing away money.

I agree- u couldn’t pay me to cut off a functioning cell plate!
A simple timer is the answer here

 

[Shirker]

which runs continuously

Why?

You do have a variable speed pump, right? If not, a VS will save you a lot of electricity. They pretty much all have timers already built in and/or have the ability to plug into an automation center.. If your pump runs 24/7, then your only knob to turn is on your SWCG. A pump timer gives you another variable to control which makes balancing your chlorine generation a lot easier.

 

[Mdragger88]

That unit’s output is also adjustable in 25% increments
Most residential pools consume 2-4 ppm of fc daily
That unit - before u cut any plates -produces 1.88 lbs/day
It Only needs to run 5-6 hrs/day @ 100% to produce sufficient fc to replace a daily loss of 2-4ppm possibly less considering u have a cover.
Or it could be run on the lowest setting (25%) for 24 hrs
U can play around with runtimes & percentages in PoolMath effects of adding in the menu.

Either way u just need to reduce the % or runtime.
It’s possible that since u cut the plates that u also affected the way the cell is designed to clean itself automatically by reversing its polarity.

 

[ibseanb]

Thanks for all the replies. I'll get the levels and report back. I have the Taylor K 2006 kit; I bought it last year when dealing with algae.

I do have a Haward variable speed pump, it runs 24/7 on low speed, and the SWG is connected to the same 220 terminal inside the pump. Basically, the wires come from the circuit breaker, into the pump where both the pump and SWG are tied into the same screws. It has no ability to turn on/off the SWG based on its speed from what I know. The SWG has an on/off toggle and strength settings only.

I was going to hook up a 220 V timer to the SWG only, and keep the pump running constantly as it always has.

 

[markayash]

Thanks for all the replies. I'll get the levels and report back. I have the Taylor K 2006 kit; I bought it last year when dealing with algae.

I do have a Haward variable speed pump, it runs 24/7 on low speed, and the SWG is connected to the same 220 terminal inside the pump. Basically, the wires come from the circuit breaker, into the pump where both the pump and SWG are tied into the same screws. It has no ability to turn on/off the SWG based on its speed from what I know. The SWG has an on/off toggle and strength settings only.

I was going to hook up a 220 V timer to the SWG only, and keep the pump running constantly as it always has.

Good idea, maybe the expert folks know but is a power supply designed for a certain size cell?

My SWG will run on 120 so I just added a plug and setup a smart outlet so I can change it when needed.

 

[jmastron]

I think "Open up the cell and cut off plates" wins the award for "craziest advice given by pool store or industry people"

Do you have the SWCG set to the lowest strength (25% if the controls are like this https://waterlinetechnologies.com/c...nerator-up-to-60-000-gallons-52000-260-000/)? It is possible that with a smaller pool and large SWCG running 24 hours a day, your chlorine demand per day could be less than even 25%. Nothing wrong with that (the cell should last even longer), but the runtime does need to be reduced.

A good alternative to the 220V timer that involves a bit less hard-core electrical work is to rewire the SWCG to 120V and plug it into any $15 WiFi outdoor plug. But either is far better than hacking (literally) into the cell IMO.

I'd highly encourage you to get us a full set of test results (from your own kit); people here may have some other suggestions. For example, I'll be interested to see your CYA level -- that will both give a hint as to how much chlorine demand per day you have, as well as the recommended level to maintain FC at.

 

[Mdragger88]

I think "Open up the cell and cut off plates" wins the award for "craziest advice given by pool store or industry people"

Right ?
Goes to show - they already got your $$ & couldn’t care less what happens to your pool.

 

[markayash]

This is what I did, power come from same power feed as pump to limit the risk

 

[ibseanb]

Ok, here are the numbers:

• FC: 3.6 (had the SWG off overnight)
• CC: 1
• TA: 180 with a 25ml sample, 175 with a 10ml sample
• PH: 7.8
• CYA: Could not get the black dot to disappear, so <30
• Calcium: 280
• Temp: 87

My source water is high in TA from the well. This year we've noticed tiny brown circle stains at the bottom of the pool in a few locations. Iron? Last year I took my water to the pool company and they said I had a bit of copper in the water also.

 

[proavia]

Chances are it took longer to cut plates off the SWG (and void the warranty) than it would have taken to install a timer for the SWG.

 

[ibseanb]

Chances are it took longer to cut plates off the SWG (and void the warranty) than it would have taken to install a timer for the SWG.

Not really, a good set of sheet metal snips made quick work of it.

 

[Mdragger88]

Ok, here are the numbers:

• FC: 3.6 (had the SWG off overnight)
• CC: 1
• TA: 180 with a 25ml sample, 175 with a 10ml sample
• PH: 7.8
• CYA: Could not get the black dot to disappear, so <30
• Calcium: 280
• Temp: 87

My source water is high in TA from the well. This year we've noticed tiny brown circle stains at the bottom of the pool in a few locations. Iron? Last year I took my water to the pool company and they said I had a bit of copper in the water also.

Getting things inline with recommended levels is the 1st step.

What Are My Ideal Pool Levels?

Use our tool to find ideal chemical levels for any swimming pool. Check TFP recommended levels on pH, free chlorine, cyanuric acid, and more.

www.troublefreepool.com

Along with managing csi to prevent scaling - which will come inline with the addition of cya & keeping ph balanced.

Calcium Saturation Index (CSI)

How is CSI calculated? Very simple – by using the PoolMath tool. To ensure long plaster life and save money, click here to learn more

www.google.com

With the cover deployed most of the time u likely don’t need a cya of 70 but u do at least need some - try 30 or 40ppm & chlorinate accordingly FC/CYA Levels
As mentioned, adjust the run time & or percentage on the swg to maintain fc @ target or a scootch above for your cya.
Your pump only needs to run long enough to effectively remove debris & for your swg to produce adequate fc.

Here’s how to lower ta safely

Lower Total Alkalinity

A lower Total Alkalinity level can help a pool owner stabalize their pH increase. We'll explain how to lower TA with a little help from muriatic acid.

www.troublefreepool.com

 

[ibseanb]

Thanks for the replies. I have been busy trying to get the levels down to recommended values.

Over the course of a few days, I added a half gallon of muriatic acid, and read levels the next day. TA and PH dropped, but not by as much as I wanted. I added the other half gallon and repeated. Still was a bit high, but PH was down to 7.
It rained a bit, and PH went back up and TA was still elevated, so I added more acid.

Also, I added 2lb of CYA into the skimmer into an old white shirt and let it run for a day. It must have been close to 0 before, because it's still not registering. I just added another 2lb and letting it run again.

I have kept the cover open, with the SWG at 25%. The water level was a bit low so I was hoping that the last day or so of rain would help get fresh (Low TA) water into the pool without having to add from my (High TA) well water.

• FC: 4.0
• CC: .2
• PH 7.2
• TA: 140
• CH: 260
• Temp: 84
• CYA: 0